Worsted/synthetic stretch fabric and process for manufacturing same



United States Patent 3,153,838 WORSTED/ SYNTHETIC STRETCH FABRIC AND PROCESS FGR MANUFACTURING SAME Marvin J. Pinson, Jr., Raeford, N.C., assignor to Burlington Industries, 1:19., Greensboro, N.C., a corporation of Delaware No Drawing. Filed Jan. 11, 1963, Ser. No. 250,759 11 Claims. (Cl. 28-72} The present invention relates to worsted stretch fabric and novel procedures for preparing same.

Woven stretch fabrics are becoming increasingly important in the clothing industry, for example, as suiting material or in leisure apparel and sportswear. The principal object of the present invention is to provide certain unique improvements in the preparation of worsted/synthetic stretch fabric. A more specific object is the provision of a process for preparing a worsted stretch fabric comprising worsted/ polyester or worsted/ nylon yarns. Other objects will also be hereinafter apparent.

The objects of the invention are realized by the use of a unique combination of features. These features include a specially prepared composite stretch yarn comprising at least one essentially twist-free core of textured, e.g. crimped, synthetic thermoplastic multifilament polymer yarn covered and interlocked with spun fibers, the latter being either 100% worsted fibers or a blend of worsted fibers with other natural or synthetic staple fibers. Another unique and important aspect of the invention is the feature of reeding out in weaving, i.e. increasing the space between the warp ends in the loom reed so that when the fabric is woven and relax finished, the filling yarn is allowed to bulk and the warp ends w ll be drawn in closer together thus providing a stretch fabric that will elongate and contract. Additionally, the fabric construction must be such that the sum of the average number of picks and warp ends per inch for any particular weave does not exceed a definite maximum. These and other features of the invention are discussed in more detail below.

Broadly stated, the invention involves preparing a worsted/synthetic stretch fabric by a process which includes the steps of (1) providing a composite stretch yarn made up of an essentially twist-free core of crimped or otherwise textured synthetic thermoplastic multifilament yarn and spun yarn comprising either 100% worsted fibers or blends of worsted with other natural or synthetic staple fibers wherein the fibers are suificiently interlocked with each other to cover or seal the core; (2) weaving a fabric with both filling yarn and warp yarn under tension using the'stretch-core yarn at least as the filling yarn and, if desired, as the Warp yarn with the Warp yarn reeded out so that the filling yarn can bulk when the fabric is relax finished; (3) maintaining the total number of the picks and warp ends per inch of said fabric below a predetermined maximum during the weaving operation and, after weaving is completed, (4) finishing the resulting fabric in the completely relaxed state.

If the composite worsted/ synthetic stretch yarn is used as both filling and warp, the resulting fabric will have stretch lengthwise and widthwise. However, it is preferred to use this tretch yarn only as the filling along with conventional worsted or worsted/synthetic yarn as the warp to give a worsted/ synthetic fabric which only stretches widthwise. The stretch can be controlled from 12 to 24% by adjusting construction and finish although it willbe recognized that the degree of stretch can be varied'as desired depending on the amount of reeding out, the type of weave, the yarn used and other factors.

The invention permits the preparation of fabric constructions which vary rather substantially. However, as noted above, it is essential to have a certain balance between the number of picks and ends per inch and this is effected by insuring that a predetermined maximum is not exceeded for the sum of the average number of picks (fill ing threads per inch) and end (warp threads per inch) sley. This maximum will vary depending on the yarn count and type of Weave but a definite value can be calculated for any specific circumstance and should not be exceeded if a satisfactory stretch fabric is to be obtained.

This maximum, Which may also be called the maximum average loom fabric construction may be determined for any particular type of weave and yarn count by the f0llowing formula:

(W) on y+n wherein M is the maximum average loom fabric construction or maximum average of the sum of the picks and ends per inch;

x i the yards per pound determined by multiplying the equivalent count of the stretch filling yarn by 560 (worsted hank);

y is the number of ends in a repeat of the pattern;

n is the number of interlacings per end in the weave, interlacings being defined as the number of intertwinings or crossings that one end of the weave makes with the filling in one repeat of the pattern; and

B is the percent warp contraction depending upon weave and picks per inch. This value is obtained by subtracting the length of the greige woven material from the length of the dressed or beamed material. In other words, if the greige material has a length of yards and the beamed or wound length of warp yarn on the loom beam is yards, the warp contraction (b) is .10 in the above formula.

The manner in which the above formula is used to determine the value of M is shown below using for purposes of illustration a so-called 1 x 1 weave (FIGURE 1, page 730 of The Modern Textile Dictionary by George Linton). A weave of this type has two ends in a repeat of the pattern and two interlacings per end in the pattern. Using as the filling, a stretch worsted/ synthetic yarn having an equivalent worsted count of 30, the maximum sum of the average number of picks and ends per inch can be calculated as follows, the B value being 10% for this given fabric:

times 2 117 Thus, using warp and filling yarn of the type indicated for a 1 x 1 weave, the sum of the average picks and ends (or sley) per inch should not exceed a value of 117. This represents the maximum average loom fabric construction which will give a stretch fabric as contemplated herein and any number of picks and ends per inch may be used provided their sum is below the calculated maximum. Thus, the minimum average loom fabric construction may be any reasonable value which gives a usable fabric, usually not below 50% of the calculated value of the maximum loom fabric construction and will depend in any particular case on the type of product desired. v

The synthetic multifilament yarn used as the core yarn herein may comprise nylon or polyester, e.g. (Dacron), or other thermoplastic materials characterized by plastic memory. This yarn may be crimped or otherwise textured in known manner, e .g., by the so-called Helanca, Ban-Lon, Agilon, Superloft and Flufion methods, all of which involve heating the thermoplastic yarn when in a crimped, looped or twisted condition so that it is permanently set in the deformed state due to its plastic memory.

The core yarn is desirably a 70 denier Dacron poly ester or nylon multifilament yarn although other yarn M times 2 deniers, for example, 20 to denier multifilament nylon yarn with the number of filaments ranging from 7 to 68, may be used effectively. Commercially available 70 denier multifilament Dacron polyester yarn normally includes 14 or 34 filaments and both of these types may also be used for present purposes. Normally, the core yarn will comprise from about 10 to 45% by weight of the final composite worsted/synthetic stretch yarn and the core yarn will be covered completely with the spun fibers in both the relaxed and taut conditions.

As indicated above, the core covering may be either 100% worsted fibers or a blend of worsted fibers with some other natural and/ or synthetic staple fibers. For blend purposes, a variety of other fibers may be used with the worsted fibers, such as nylon or cotton staple, but polyester staple (e.g. Dacron) is preferred. The composition of these blends can be widely varied and the amount of, for example, polyester staple therein for any specific situation will depend on other operating factors such as the nature of the product desired, the core yarn, etc. Generally speaking, blends will comprise as much as 70% by weight or even more (e.g. 90%) of polyester staple and/or non-worsted staple with the balance wool. One preferred blend comprises 50% wool fibers and 50% polyester staple although it will be appre cited from the foregoing that these percentages can be varied. Commercially available forms of polyester staple or converted tow or the like may be used to make up these blends. One typical example of suitable Dacron polyester staple may be prepared in the form of 3 denier, semi-dull 4.5 inch fibers.

The wool fibers used to cover the crimped or textured core yarn should have a grade number between 62 and 80 USDA wool standards. The same limits should be observed if conventional worsted/synthetic or 100% worsted yarn is used as the warp. The equivalent count of the stretch worsted/synthetic yarn as woven herein in warp or filling will normally be between 10 and 45.

The stretch worsted/ synthetic yarn may be prepared in either of two ways. In the first method, the crimped or otherwise textured yarn (e.g. 70% denier 14 filament Dacron polyester yarn) with twist therein is fed into the center of, for example, a 100% worsted roving as the roving is passed into the conventional front drawing roll of the spinning frame and hence spun into yarn. As known in the art, roving is normally spun as it leaves the drawing rolls thereby forming worsted yarn. In the present case, the roving containing the core yarn in its center is twisted as it emerges from the front drawing roll of the spinning frame so that the resulting stretch worsted/synthetic yarn has a spun twist amounting to at least 10 and no more than 24 turns per inch. This twist may be in either the S or 2 direction.

After the worsted/synthetic yarn is formed, the twist is stablized by a wet heat treatment with steam (saturated) at 65 C. to 77 C., for from 45 to 90 minutes. The thus stabilized product is then plied with another similarly stabilized worsted/synthetic yarn which is identical to the first worsted/ synthetic yarn in all respects, including the amount and direction of the twist spun therein. The ply twist should be in the opposite direction from that of the pre-plied yarn components and should be substantially equal to the preply twist spun into the worsted/ synthetic yarn. In other words, if the worsted/ synthetic yarn is spun with a twist in the 8 direction, the ply twist should be in the Z direction but substantially equal to the spun twist. This is an important factor in preparing the plied yarn because the success of the invention requires that the textured core yarn be substantially free of twist. Normally, it is sufficient to ply back substantially to the zero twist point plus or minus turns in either direction if desired. a

It will be appreciated that the resulting stretch worsted/ synthetic yarn is a two-ply product comprising an essentially twist-free synthetic core and an outer covering made up entirely of wool fibers or a blend thereof with yarn.

4 polyester or other staple, the fibers in any event being completely interlocked with each other to cover or seal the core. If desired, the stretch worsted/synthetic yarn may include more than two plies, e.g., three, four, five or six by simply plying together the desired number of worsted/ synthetic yarns having the same degree and direction of twist spun therein, in the manner outlined above. The resulting multi-ply stretch worsted/ synthetic yarn product may then be used directly as the filling or warp yarn for weaving the stretch fabric of the invention as hereinafter described.

The second way of preparing the stretch/worsted lsynthetic yarn used herein involves the preparation of a single-ply yarn rather than two-ply or multi-ply yarn. According to this second method, the crimped or textured synthetic multifilament yarn, e.g. polyester yarn with essentially zero twist therein, while under crimp-removing tension, is first given a post twist which puts from 8 to 20 turns per inch in the crimped yarn. The twist may be in either the S or 2 direction. Thereafter, this twisted yarn is fed, while still under tension, into the center of a roving (100% worsted or blend as described above) which is being spun into yarn, with a twist in the opposite direction from the post twist in the synthetic multifilament The twist applied during the spinning should be substantially equal to the post twist initially applied to the core yarn. In other words, if the core yarn is post twisted 15 turns Z, the roving should be spun with preferably 15 turns in the 8 direction or within a range of 10 to 20 turns in the 8 direction. This takes practically all of the initial twist out of the core yarn and leaves it essentially twist-free. The roving fibers are twisted so as to interlock with themselves and completely cover and seal the core yarn in the relaxed and taut condition. After stabilizing as described before, this product may be used directly as the filling yarn, as well as warp yarn, in preparing woven stretch fabric according to the invention.

Apart from the reeding out feature referred to above and the indicated limit in the total number of picks and ends, the fabric of the invention may be woven using generally standard techniques and apparatus. After the weaving operation, however, it is essential that the resulting greige Worsted fabric be finished, e.g. scoured, under conditions providing for complete fabric relaxation and absolute thermal control in each phase of the finishing operation. 'By thermal control, it is intended to mean that specific temperatures are applied for each phase of the finishing process.

In the usual case, the following finishing operations are carried out, generally in the order indicated, the terminology utilized being standard in the trade as shown, for example, in The Modern Textile Dictionary by George Linton:

(l) Batching, i.e. putting together different quantities of woven material which are to be processed together;

(2) Singe, the woven fabric being passed over a series of gas jets or hot plates to remove protruding fibers;

(3) Birch crab under controlled temperature. This 7 involves running the cloth into a series of hot water baths or bowls' of increasingly higher temperature with cooling in the final water bath or bowl. The purpose of this operation is to set the yarns in the material and to prevent ordinary shrinkage. In the case, of a seven bowl Birch crab, the speed of the fabric is preferably about 30 yards per minute and usually within the range of 23 to 35 yards per minute depending on the type of fabric. Typical operating temperatures for the seven (4) Yorkshire crab. This involves setting the fabric in boiling water usually for from five to fifteen minutes, preferably about ten minutes;

(5) Pin dry relaxed. This comprises drying with warm air without tension at 115-125 C., at -25 yards per minute, preferably 123 C., at 20 yards per minute. The fabric is usually subjected to the above drying tem peratures for approximately five minutes;

(6) Heat set. This may be done in a drier (e.g. a Famatex drier) under dry heat setting conditions, such as 200220 C., in the relaxed condition;

(7) Scour in dye kettle using a non-alkaline, e.g. neutral, nonionic detergent. Usually the scouring is carried out at 60 C., for from 25 to minutes, preferably about C. for 30 minutes, followed by rinsing with water, treating in boiling water for 30 minutes and then dyeing;

(8) The fabric is then again pin dry relaxed as before;

(9) Screen. This operation involves a visual examination of the fabric to ascertain if the preceeding processes met quality standards and to repair if necessary torn selvages, seams, etc., that might be more seriously damaged in subsequent operations;

(10) Shear, i.e. cutting off the undesired protruding fibers on the surface of the cloth;

(11) Heat set relaxed as before under item (6);

(12) The fabric is then subjected to a cold water shrinkage operation. This comprises immersing the fabric in a bath of cold water containing a wetting agent at, for example, 32 C.;

(13) The finishing operation is continued by loop drying which is characterized by drying with warm air without tension at 1l5125 C., preferably 123 C., at 2025 yards/minute, preferably 20 yards per minute. The fabric is usually subjected to the above drying temperature for approximately five minutes;

(14) The cold water shrinkage operation and loop drying procedures mentioned above are repeated;

(15) Full decating' by autoclave pressure steaming, for example, at 10 psi. for 3 minutes followed by 8 minutes cooling.

Most, if not all, of the above-noted finishing steps are known, in and of themselves, in the worsted fabric art. However, it is a characteristic requirement of the present process that the essential finishing operations, and notably those involving a liquid or drying treatment, must be carried out with the fabric in a completely relaxed state and in sequences, temperatures and time cycles as described above.

The invention is illustrated, but not limited, by the following examples:

Example 1 A 70 denier 14 filament polyester yarn (Dacron) crimped by the Superloft process but having substantially no twist therein was introduced under controlled tension (15 to 20 grams) into the center of one 100% worsted drafted roving end just prior to the front drawing roll of the spinning frame. The roving was made up of 70 grade wool. The roving containing the polyester core yarn in the center thereof was spun into yarn having a yarn count of 30 and a twist of 18 turns in the 8 direction. The resulting yarn was then treated with saturated steam at 75 C. for 60 minutes and then plied with another identical stretch worsted/polyester yarn having 18 turns of twist in the 8 direction. Both of these yarns comprised a polyester core covered with worsted fibers, the worsted fibers comprising about 67% by weight of the composite product. The plying operation was carried out with the yarns in the taut condition (e. g. between 10 and 30 grams as measured, on a Model 2804 Sipp-Eastwood Corporation tensiometer, between the point where two or more pre-ply ends are stabilized in tension and the point where ends are delivered to the final ply twisting guides.) The ply twist amounted to 16 turns in the 2 direction. As a result, the polyester core and worsted covering of this two-ply product were essentially twist-free, the total twist amounting to 2 turns 8.

The two-ply product was then used as the filling yarn in a 1 x 1 weave. The warp yam was 2/30 60/58s worsted yarn, the pre-ply yarn spun 16 turns 2 twist and plied 14 turns 8 twist. Before weaving, the maximum figure for the sum of the average picks and ends per inch was calculated using the formula given heretofore. The two-ply filling yarn measured approximately 8,400 yards per pound giving an equivalent count of about 15. Thus, the value M is calculated as follows, the value of B being 10%:

w times 2 83 The fabric was woven with the warp yarns reeded out sufiiciently to permit the filling yarn to bulk when the fabric was relax finished. This caused the fabric to narrow approximately 25% in width when relaxed. This means that the fabric when taut would stretch out a substantially equivalent amount from the relaxed state. The reeding out used in this example meant that the warp ends were spaced from 10 to 12% farther apart than in a similar non-stretch type of fabric. The reeding out also helped maintain the total number of picks and ends per inch below the maximum calculated value of 83 necessary to obtain optimum results.

After the weaving operation, the greige fabric was taken from the loom and finished as follows: batched with additional fabric made in the same way, flame singed, subjected to the Birch crab and Yorkshire crab, pin dry relaxed, heat set, scoured neutral and boiled in a dye kettle, dyed, again pin dry relaxed, screened, sheared and heat set, all as mentioned heretofore. Following this heat setting, the fabric Was subjected to repeated cold water shrinkage and loop drying, followed by full decating, also as heretofore.

The thus finished product comprised a highly attractive worsted/ polyester fabric possessing inherent stretch characteristics in the filling direction. Clothing made from this fabric is characterized by comfort and stability. The fabric returns to its original shape after being stretched and demonstrates no adverse changes after tailoring, wearing and repeated dry cleaning.

Substantially equivalent results are obtained by replacing the polyester yarn with 70 denier, 17 filament nylon yarn crimped by the Helanca method. Similar results are also obtained using as the filling yarn a single ply worsted/polyester or worsted/nylon yarn prepared by post twisting crimped or textured polyester or nylon yarn with, for example, 15 turns S twist per inch and then using this twisted yarn as the core yarn in spinning a stretch worsted covered core yarn with 18 turns 2 giving a resultant twist of 3 turns 2 in the core yarn.

Example 2 Example 1 was repeated except that, in place of the worsted roving, there was used a blend of 50% wool fibers and 50% T64 Dacron polyester staple (semidull, 3 denier, 4.5 inch fibers).

The resulting products were extremely attractive with excellent stretch characteristics in the filling direction.

This application is a continuation-in-part of my earlier application Serial No. 173,341, filed February 15, 1962, now abandoned.

It will be appreciated that various modifications may be made in the invention described herein without deviating from the scope thereof as set forth in the appended claims wherein I claim:

1. The method of preparing a worsted stretch fabric which comprises (1) providing a composite stretch yarn made up of a core of textured synthetic thermoplastic multifilament yarn essentially free from twist and covered with spun yarn comprising worsted fibers and (2) weaving a fabric using said stretch yarn at least as the filling yarn, the warp yarn being reeded out so that said filling yarn is'provided space to bulk when the fabric is finished, the sum of the average picks and ends per inch of the woven fabric being not greater than x (y) 1-B time, 2

y+ wherein M is the maximum sum of the average of the picks and ends per inch; x is the yards per pound determined by multiplying the equivalent count of the filling yam by 560'; y is the number of ends in a repeat of the pattern; n is the number of interlacings per end in the weave;

and B is the percent warp contraction depending on the Weave and picks per inch.

x 2. The method of claim 1 wherein the spun yarn is 100% worsted.

3. The method of claim 1 wherein the spun yarn is a blend of Worsted fibers and other staple fibers.

4. The method of claim 3 wherein the other staple fibers are polyester fibers.

5. The method of claim 1 wherein said multifilament yarn is selected from the group consisting of polyester and nylon yarns.

6. The method of claim 1 wherein the warp yarn is 100% worsted.

7. The. method of claim 1 wherein said composite stretch yarn is prepared by first twisting said textured core yarn in one direction, thereafter feeding said twisted core yarn into the center of one roving end containing worsted fibers and spinning the same into a composite yarn having a spun twist therein in the opposite direction to the twist applied to said core yarn and substantially equal thereto.

8. The method of claim 1 wherein said composite stretch yarn is'prepared by feeding said textured core yarn with zero twist therein into the center of one roving containing Wool fibers, spinning a worsted/synthetic core yarn from said core yarn and roving having a spun twist therein, and thereafter plying two such worsted/ synthetic core yarns, the ply twist being opposite to and substantially equal to the twist spun into said worsted/synthetic core yarns before plying.

9. The method of claim 1 wherein the woven fabric is finished in the completely relaxed condition.

. 10; The stretch fabric obtained by the :method of claim 1. 1

11. The method of preparing a worsted stretch fabric which comprises (1) providing a composite stretch yarn made up of a core of textured synthetic thermoplastic multifilament yarn essentially free from twist and covered with spun yarn comprising worsted fibers; (2) weaving a fabric using said stretch yarn at least as the filling yarn, the warp yarn being reeded out so that said filling yarn is provided space to bulk when finished, the sum of the average picks and ends per inch of the Woven'fabric being not greater than wherein M is the-maximum sum of the average of and ends per inch;

x is the yards per pound determined by multiplying the equivalent count of the filling yarn by 560;

y is the number of ends in a repeat of the pattern;

It is the number of interlacings per end in the weave;

and

B is the percent warp contraction depending on the weave and picks per inch;

the picks and (3) finishing the woven fabric by liquid treatment and heat setting in the completely relaxed condition.

References Cited in the file of this patent UNITED STATES PATENTS 2,134,022 Bell Oct. 25, 1938 2,153,964 Lejeune Apr. 11, 1939 2,177,586 Voegeli Oct. 24, 1939 2,330,645 Voegeli Sept. 28, 1943 2,574,029 Foster Nov.- 6, 1951 2,810,184 Sherman Oct. 22, 1957 2,901,884 Weinberger et al. Sept. 1, 1959 2,971,322 Bouvet Feb. 14, 1961 2,985,940 Weldon May 30, 1961 3,038,295 Humphreys June 12, 1962 3,070,950 Thomas Ian. 1, 1963 V FOREIGN PATENTS 781,344 Great Britain Aug. 21, 1957 850,059 Great Britain Sept. 28, 1960 870,017 Great Britain June 7, 1961 

11. THE METHOD OF PREPARING A WORSTED STRETCH FABRIC WHICH COMPRISES (1) PROVIDING A COMPOSITE STRETCH YARN MADE UP OF A CORE OF TEXTURED SYNTHETIC THERMOPLASTIC MULTIFILAMENT YARN ESSENTIALLY FREE FROM TWIST AND COVERED WITH SPUN YARN COMPRISING WORSTED FIBERS; (2) WEAVING A FABRIC USING SAID STRETCH YARN AT LEAST AS THE FILLING YARN, THE WARP YARN BEING REEDED OUT SO THAT SAID FILLING YARN IS PROVIDED SPACE TO BULK WHEN FINISHED, THE SUME OF THE AVERAGE PICKS AND ENDS PER INCH OF WOVEN FABRIC BEING NOT GREATER THAN 